Hot Cathode’s Working Voltage Impacts on the Operation of High Current Ion Source

High power ion source is one of the important parts of the neutral beam injection. It produces high energy beam by extracting and accelerating ions from its arc chamber. The hot cathode (filaments) in the arc chamber of the ion source operates in two modes. Operation mode of the cathode has great effect on the stable operation of the ion source. Based on the theory of hot cathode and experimental results, this paper presents the operation results (beam current, arc efficiency) of an ion source with various cathode temperatures (controlled by voltage applied to the cathode).     

Investigation of Arc Regulation of Hot Cathode Ion Source with Langmuir Probe

The neutral beam injector (NBI) is one of the main plasma heating methods for nuclear fusion devices. For the hot cathode high current ion source, the arc current and beam current tends to increase during the beam pulse. In order to gets long pulse beam extraction, the arc regulation technology is employed. The Langmuir probes are installed on the experimental advanced superconducting tokamak-NBI ion source, to feedback control the arc discharge and beam extraction. The experimental results show that, the long pulse of 100 s ion beam is extracted with beam energy of 30 keV with arc regulation. More the results are presented in this paper.     

Study the Characteristic of the Hot Cathode of High Current Ion Source

The difference of hot cathode operation mode has great influence on the arc discharge of high current ion source. Based on the analysis of the theory of hot filament with two operation modes and combined with ion source experiments, the paper studies the effects of hot filament operation modes on ion source arc discharge.     

低能高束流氩离子源的结构及性能

离子源技术是等离子体研究中的一项重要内容,而低能大束流源则是离子源技术研究中的一个重要方向,因为这样的源在离子束刻蚀、离子束溅射镀膜以及荷能粒子与物质相互作用方面都有广泛的应用;本文采用空心阴极空心阳极结构,用热阴极电子发射弧放电驱动并用磁场约束产生等离子体,用曲面发射引出离子束,研制成了氩气放电溅射离子源;研究了灯丝加热电流、弧压对弧流的影响和弧流与工作气体压力对离子束引出的影响规律.离子源的引出电压在0-4.0 kV之间连续可调,最大引出束流为100 mA,束斑面积为φ6.0 cm,以Ti为溅射靶时的最大溅射沉积率为0.45 nm/s,离子源可连续工作160 h.     

Investigation of Vacuum Arc Voltage Characteristics Under Different Axial Magnetic Field Profiles

Characteristics of the arc voltage under different profiles of axial magnetic field were investigated experimentally in a detachable vacuum chamber with five pairs of specially designed electrodes generating both bell-shaped and saddle-shaped mafnetic field profile. The arc column and cathode spot images were photographed by a high speed digital camera. The dependence of the arc voltage on arcing evolution is analyzed. It is indicated that the axial magnetic field profile could affect the arc behaviors significantly, and the arc voltage is closely related to the arc light intensity.     

Characteristics of Single Cathode Cascaded Bias Voltage Arc Plasma

A single cathode with a cascaded bias voltage arc plasma source has been developed with a new quartz cathode chamber,instead of the previous copper chambers,to provide better diagnostic observation and access to the plasma optical emission.The cathode chamber cooling scheme is also modified to be naturally cooled only by light emission without cooling water to improve the optical thin performance in the optical path.A single-parameter physical model has been developed to describe the power dissipated in the cascaded bias voltage arc discharge argon plasmas,which have been investigated by utilizing optical emission spectroscopy(OES) and Langmuir probe.In the experiments,discharge currents from 50 A to 100 A,argon flow rates from 800 sccm to 2000 sccm and magnetic fields of 0.1 T and 0.2 T were chosen.The results show:(a) the relationship between the averaged resistivity and the averaged current density exhibits an empirical scaling law as η∝ j~(-0.63369) and the power dissipated in the arc has a strong relation with the filling factor;(b) through the quartz,the argon ions optical emission lines have been easily observed and are dominating with wavelengths between 340 nm and 520 nm,which are the emissions of Ar~+-434.81 nm and Ar~+-442.60 nm line,and theintensities are increasing with the arc current and decreasing with the inlet argon flow rate;and(c) the electron density and temperature can reach 2.0 × 10~(19) m~(-3) and 0.48 eV,respectively,under the conditions of an arc current of 90 A and a magnetic field of 0.2 T.The half-width of the n_e radial profile is approximatively equal to a few Larmor radii of electrons and can be regarded as the diameter of the plasma jet in the experiments.     

Production of Multiply-Charged Ions of Ne, Ar, Kr and Xe by the Electron-Bonbarded Hot Cathode IoN Source of IPCR

Production of multiply-charged ions of Ne, Ar, Kr and Xe has been studied by use of an electron-bombarded hot cathode type ion source of the IPCR 160cm cyclotron, which is similar to Morozov's source. These multiply-charged ions were accelerated by a 3rd harmonics acceleration mode in the cyclotron and detected with a beam probe fixed at the radius of 55cm. Observed multiply-charged ions are Ne2+, Ne3+, Ne4+, Ne5+, Ar3+, Ar4+ Ar5+, Ar6+, Ar7+, Ar8+, Kr6+, Kr7+, Kr8+, Kr9+, Xe9+, Xe10+ and Xe11+. Relative abundance of each charge state of four elements were measured. In case of Kr and Xe , the intensity of observed multiply-charged ions decreased to 1/3 or 1/4 when the charge number is increased by one. Intensities of Ar4+, Ar6+, Ar8+, Kr6+ and Kr8+ were measured as a function of the operation conditions of the ion source, such as arc voltage, arc power and gas flow rate. It was found that a smaller gas flow and a higher arc power brought about a higher yield in all the measured ions. Obtained current intensities of ion source output are 40?A Ar8+, 600?A Kr6+, 40?A Kr9+, 150?A Xe9+ and 10?A Xe11+ respectively.     

Parametric Study on Arc Behavior of Magnetically Diffused Arc

A model coupling the plasma with a cathode body is applied in the simulation of the diffuse state of a magnetically rotating arc.Four parametric studies are performed:on the external axial magnetic field (AMF),on the cathode shape,on the total current and on the inlet gas velocity.The numerical results show that:the cathode attachment focuses in the center of the cathode tip with zero AMF and gradually shifts off the axis with the increase of AMF;a larger cathode conical angle corresponds to a cathode arc attachment farther away off axis;the maximum values of plasma temperature increase with the total current;the plasma column in front of the cathode tip expands more severely in the axial direction,with a higher inlet speed;the cathode arc attachment shrinks towards the tip as the inlet speed increases.The various results are supposed to be explained by the joint effect of coupled cathode surface heating and plasma rotating flow.     

A Source for Multiply-Charged Ions and Acceleration of C, N and O Ions by IPCR Cyclotron

The design and performance of the ion source which is now used in the IPCR variable energy cyclotron are described. The source is of the electron-bombarded hot cathode type having two cylindrical cathodes of tungsten and a water-cooled copper anode containing a replaceable molybdenum slit plate. The arc discharge is established continuously but not pulsed. The source is usually operated very stably under an arc power of 1.5 to 3kW with a gas flow rate of 1 to 2 cc/min. The lifetime of the source is mainly limited by the erosion of the upper tungsten cathode at about 24 hours. At present, C4+, N4+, O4+, N5+ and O5+ ions are accelerated up to 48~100, 56~1100, 70~95, 56~125 and 70~125 MeV respectively, and a few micro-amperes of these ions are extracted from the cyclotron. The vacuum obtainable in the accelerating chamber is usually 2 ~ 4 × 10-6 mHg, and the loss of ion beam by the charge exchange effect is comparatively small. Extracted ion beams are used in several experiments for about 1900 hours in a year.     

Duoplasmatron Ion Sources

A survey on questions related to the production of multiply charged ions with the Duoplasmatron ion source is given. In spite of differences of the multiply charged ion source and the mass separator type, design considerations show that high containment is a common feature to be attained in both subjects. Multiply charged metal ions are produced by material evaporation into the magnetically confined anodic plasma and auxiliary gas feed into the cathode discharge regions. Energy spreads of ion beams from the low and the high arc current source are compared. The Duoplasmatron ion source proves to be a hygieneous source of high containment that permits the production of medium charge states up to 9+ for xenon at modest energy spread and good brilliance of the extracted ion beam in a high current-low voltage discharge mode.     

真空弧离子源脉冲工作瞬间的放电行为

采用高速摄影和光谱诊断的方法研究了真空弧离子源脉冲工作瞬间的放电行为。拍摄了离子源放电瞬间吸氢电极上阴极斑的形成过程，分析了不同放电电流时阴极斑的发射光谱。实验结果表明，当脉冲工作电流为10^1—10^2A时，真空弧离子源放电区一般只有单个阴极斑，阴极斑的位置在同一次放电中的变化很小；较大的脉冲工作电流有利于提高阴极斑的温度，并最终导致氢离子浓度的增加，但也会使阴极材料的溅射更加严重，造成离子源等离子体品质下降。     

强流双潘宁离子源弧特性研究

针对22cm双潘宁离子源,研究了其弧流与放电调节参数的关系以及二次进气的效果,确定了拉长弧流脉宽、提高弧流强度与稳定性、达成离子源合适工作状态的措施,为获得高品质的弧流提供了依据.离子源弧特性测试研究结果对提高强流离子源的工作性能以实现NBI系统强流准稳态运行有重要的指导意义.     

The Arc Model in SiO2 Current-limiting Fuse

1. IntroductionIn comparison with other switching appliances,fuse is extraodinarily charasterized by a very higharc voltage and a short breaking time, produced dur-ing breaking the short circuit, therefOre, until now)on composite circuit there have been no equivalent, method of testing the capability for high voltage fuse.The test of breaking capacity for fuses requires a setof power supply which can supply high voltage andhigh current simultaneously. Por alternating current,the power supply i…     

Characteristics of a Cold Cathode Type Penning Source and Low Energy Isotope Separation of High Charge States

Measurements of voltage-, current-and gas flow dependencies of a cold cathode Penning source, using different cathode materials, are reported. The influence of the discharge parameters (arc voltage, arc current, magnetic field and gas flow) on the production of higher charge states was studied. The highest observed charge states were Ar9+ , Kr12+ Xe13+ The cold cathode type Penning source with radial extraction proves to have sufficiently low energy spread to permit isotope separation in the source-magnet field. Results for Ar2+, Kr4+ and Xe7+ as well as emittance measurements are given.     

Electrical Parameter Measurement System of the Ion Source for EAST Neutral Beam Injector

Neutral beam injection (NBI) is recognized as one of the most effective means of plasma heating. A virtual instrument (VI) has been designed to provide electrical parameter measurement for the ion source of EAST-NBI. The VI is written using the National Instruments LabVIEW graphical programming language. All data acquisition (DAQ) is accomplished using ADLINK DAQ hardware interface and Task-oriented DAQ Driver. The VI can measure filament voltage, filament current, arc voltage, arc current and accelerating voltage etc. The data obtained from the VI are feedback of the ion source operation state and helpful to direct the operation parameter optimization of the ion source.     

基于Saber的5MW中性束注入弧电源仿真设计

强流离子源是HL-2M装置5 MW中性束注入加热系统的核心部件,离子源通过弧电源加速初级电子至高能态,碰撞气体分子,产生等离子体。所以,弧电源对于离子源维持稳定的弧放电非常重要。本文利用Saber软件建立了弧电源的主电路模型,设计并仿真了弧电流的恒流控制、打坑控制以及超级电容的恒流充电控制、恒功率放电控制等。这种方法不仅提高了弧电源电路的分析和设计效率,缩短了系统研制的周期,还可用于实际系统的故障分析和控制参数的整定,降低实验风险。实验结果表明,弧电源的真实输出与仿真输出结果相符。     

HL-2AMW级中性束注入系统弧流电源设计

中性束注入是磁约束受控核聚变实验装置中加热等离子体最有效的方法之一。针对中国环流器2号中性束大功率离子源的特点,从系统功能、主电路拓扑结构、控制硬件及控制时序等方面对弧流电源进行设计。整个电源由低位移相交流调压、高压隔离降压变压器、整流滤波和电流快速转移电路4部分组成。IGBT与电阻串联组成电流快速转移阵列电路,与离子源并联,可实现电流单次或多次快速转移、参数远程设定,有效用于强流离子束的引出和保护。选用DSP和CPLD电路技术实现低位与高位控制器。实验数据显示,该电源最大输出为200kW/1000A,纹波小于2％,开关上升下降时间达μs级。目前,该电源已安全运行3年,可靠性高,完全满足装置离子源及系统要求,也可应用于其它等离子体技术应用场合。     

Characteristics of a High Current P.I.G. Ion Source at Low Gas Pressure

The characteristics of a 10 cm P.I.G. (Penning ionization gauge) discharge and its application as an ion source at a low pressure are given. Using a hot cathode two regions of operation are found, one above and the other below 1 micron. Pulsed ion current reaching 1 Ampere could be extracted from this source through a 10 cm diameter gridded cathode at a discharge current of about 20 Amperesand a gas pressure of 0.5 micron. The cathode discharge current was found to contain electrons. The ion current to the reflector cathode is about 10% of the discharge current.     

基于静电探针测量对双潘宁离子源的弧特性研究

本文介绍了采用静电探针的逐点测量法和锯齿波扫描测量法来测量离子源放电中等离子体参数,在此基础上利用静电探针所测量的离子饱和流信号作为控制部分反馈变量,使用闭环控制对22厘米双潘宁离子源的等离子体进行调节,并且利用探针所测量的结果对弧特性进行了初步的分析.     

Power Supplies for Cold Cathode Penning Discharge Ion Sources

For the generation of heavy ions at high charge states, the cold-cathode Penning discharge ion source requires a power supply capable of both the high potential essential for striking an arc and the high current for sustaining it. A series-regulated power supply developed at Oak Ridge provides up to 6 kV of striking voltage and up to 12 amperes of arc current. The power supply operates in a constant current mode with the arc voltage dependent on the gas pressure in the ion source. With this source in ORIC, the typical operating conditions are 5 to 10 amperes arc current, 600 to 2000 volts arc potential, and 5 to 20 kW power dissipation in the arc. A larger power supply is planned for extending the arc current to about 25 amperes. Various arrangements, including pre-regulators and multiple power supplies, are under consideration to reduce power dissipation in the series regulator tubes.